They're fairly easy to wire in if you have a basic understanding of electrical circuits and relays.
If not then maybe not so straightforward.
Didn't link to the transformers so that's why you can't get it to work. These are the ones I'm using
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Think I ordered them from China through either Amazon or eBay. All I will say is be careful and research when buying transformers from China. There are some bad ones about and is why I never posted a link to any as can't remember exactly where I got mine from. Any 230vac to 12vdc transformer of the required current capacity should do.
Wiring wise. Effectively it's 230v straight to the temperature controller with the live looped into the relay side of it and back out to the transformer input side and neutral straight to transformer input also. 12v transformer output connected to the fans to be controlled. Earth to everything that has an earth terminal + cabinet housing if it's metal.